Hello,
I am trying to figure out which side of the PCI slot has the riser in an R640 and other models.

I have found this documentation but they do not show which side of the PCI slot has the riser for connecting:

https://qrl.dell.com/Files/en-us/Html/R640/MechanicalOverview.html

https://qrl.dell.com/Files/en-us/html/Manuals/R640/Back%20panel%20features%20of%20a%20two%20x%202.5%20inch%20hard%20drive%20system=GUID-22AA24C5-EB47-4DF7-B24E-A6B513ACE2DB=1=en-us=.html

Is there Dell documentation for the different rear configurations with PCI connector locations listed?